I. SUMMARY II. NETWORK LEVEL ANALYSIS

Transcription

1 A omplexiy os funcion fo a newo of WDMA Basesaions using Sofwae Defined Radio wih High Speed Daa hannels. Paul Buns Ma Reed aional IT Ausalia Ausalian aional Univesiy anbea 000 AT, Ausalia paulbuns@simplexiy.com.au Absac - This pape updaes a cos funcion fo a newo of WDMA-FDD Base Saions (ode-b s) fo he pupose of dimensioning a Sofwae Defined Radio (SDR) implemenaion. This cos funcion allows fo boh a convenional diec-sequence spead specum eceive one ha uses a Muli-Use Deeco (MUD). To balance he up-lin capaciy impovemen of using MUD, Spaial Time Tansmi Divesiy (STTD) High Speed Down-Lin Pace Access (HSDPA) is consideed fo High Speed (384 bi.sec) daa channels. An SDR achiecue is poposed he cos funcion is expessed in ems of cell diamee signal pocessing load. The cos funcion is developed in ems of a lage numbe of sysem paamees including he cos of using specum. Based on ceain assumpions by implemening MUD eceives, STTD HSDPA, i is shown ha he newo cos can be educed when cell size mus be mainained above a minimum figue i.e. base saion sies ae limied. I. SUMMARY uenly he signal pocessing inensive pas of he physical laye in mos WDMA base saions (BTS s) eminals (UE s) ae implemened by fixed funcion applicaion specific inegaed cicuis (ASI s) ha have been designed fo he wos-case cell dimensions use-densiy. This wos-case allows a small se of ASI devices o mee he Laye 1 signal pocessing equiemens fo all classes of BTS. The lieaue includes many efeences fo he capaciy dimensioning of DMA ai-inefaces (including [3],[9],[5] [6]), hese all assume ha he BTS signal pocessing is dimensioned fo he wos case cell dimensions use-densiy hey do no conside he cos due o complexiy fo an SDR implemenaion. Pocedues ae developed in [7] & [8] ha minimizes he cos of a mobile newo howeve hese do no conside a sofwae adio implemenaion fo he basesaions. A sofwae adio achiecue using muli-use deecion is consideed in [9] howeve his does no conside he newo aspecs. The heoeical SDR equiemens fo WDMA ae esimaed in [] whee i is ecognized ha he signal pocessing powe of a DMA sysem inceases wih boh numbe of uses lage cell size. This efeence also does no conside he cos due o complexiy. A cos funcion [1] fo a newo of SDR BTS s has been developed by Buns Reed, howeve his assumes a specum limi of 0 MHz, is esiced o 15 bi/sec voice channels, does no conside he use of any capaciy enhancing algoihms does no conside he cos of consuming specum. This efeence [1] deemined capaciy fo he uplin only assumed ha he down-lin had equal o geae capaciy. Amplifie powe in [1] was also se o a lage nominal value o maximise coveage ahe han being opimized fo he equied capaciy coveage needs of he fowad lin. This pape, heefoe ses abou deemining a new cos funcion fo a newo of WDMA BTS s implemened using Sofwae Defined Radio (SDR) whee he basesaion s eceive ansmie ae convenionally implemened (mached file/rake), o he eceive can use a muli-use deeco he ansmie can use STTD HSDPA. The cos funcion is no specum limied also consides he cos of consuming specum. The pape shows ha: he cos funcion has a minimum coesponding opimum cell size by using MUD in he BTS eceive STTD HSDPA in he BTS ansmie, a symmeic incease in up down-lin capaciy of 80% can be achieved lage ove-all cell size is possible wih limied specum lowe cos is possible when cell size mus be mainained above he poin whee i becomes moe efficien o implemen MUD, HSDPA STTD. II. ETWORK LEVEL AALYSIS onside a poion of a WDMA cellula newo wih aea A p whee each seco coves he same aea is pefecly hexagonal. Le us assume ha he aea uses 10 degee cell secoizaion (i.e. 3 secos pe BTS). Using [11] [1] whee he BTS s ae placed in he cone of a hexagon wih diamee D, he seco aea S is hen S = D 3/ 4 (1) Assuming ha A p conains a unifom densiy of uses ρ (uses/m ) whee each use geneaes T elangs of affic duing he busies hou, each BTS in A p will be equied o suppo a maximum of T BTS elangs of affic i.e. T = 3( ρt S () BTS )

2 A omplexiy os funcion fo a newo of WDMA Basesaions using Sofwae Defined Radio wih High Speed Daa hannels Because signal pocessing esouces fo a single use ae a funcion of he seach window, i is moe inuiive o expess he seco aea using he seco adius in chips. Fo WDMA he chip ae is 3.84 Mcps, heefoe he adio wave will avel 3x10 8 /3.84x10 6 mees (~ 78 mees) along is ajecoy duing a chip peiod. In mos cellula ansmission envionmens he waves aiving a he eceive will have efleced off one o moe objecs ceaing a muli-pah envionmen whee each wave can avel a diffeen disance heefoe ae a diffeing amoun of ime, in some cases hee is no diec wave. Delay spead d is used o measue he diffeence in aival imes of he vaious mulipah waves a he eceive whee he mean vaiance is a funcion of seveal facos including physical envionmen. LA PA Seco 1 Divesiy hannel 1 Divesiy hannel 1 Seco Seco 3 Divesiy hannel Wideb Analog Muli- aie Receive Fon-End Wih AD DD's Divesiy hannel Wideb Muli-aie Analog Tansmie Fon-End Wih DA DU's Swich 1 Resouce Resouce Fig 1 SDR BTS Achiecue Bus onolle & R ineface R The seach windows fo he Pah Seach Access funcions in a WDMA eceive ae fixed in size (ime) equivalen o a discee numbe of chips c, his effecively disceizes he cell diamee. As delay inceases, wave aenuaion also ends o incease, so fo pacical puposes an uppe bound fo d is used. As he posiion of he ansmie is no nown by he eceive, Pah Seach Access funcions mus seach ove he combined up downlin diec pah ime (faco of in denominao of (3)) plus he uppe bound on delay spead. The cell diamee in mees can hen be expessed as 8 3e10 D = (3) 6 (3.84e10 (1 + )) The elaionship beween BTS seach window ime was deived in [1] as BTS 6 6 (7.68e e10 d ) = (4) (9e10 ) d Esimaes fo he level of voice affic pe uni aea ρt ae povided in [11], voice affic is classified as eihe: mobile (MS) ρt = 500 E/m, pesonal saion oudoos (PS o ) ρt = E/m o pesonal saion indoos (PS I ) ρt = E/m /floo. We assume ha high speed daa connecions duing he ealy sages of a 3G newo will be 10% of he voice connecions in his pape we use a ρt = 150 E/m (pesonal saions oudoos), his is inepeed as 150*384 Bi/sec/m. III. BTS SOFTWARE DEFIED RADIO ARHITETURE Le us assume ha he hadwae fo each BTS (see Fig1) consiss of wideb eceive divesiy channels wideb ansmi divesiy channels. Wideb is defined hee o mean ha each channel is capable of pocessing a numbe of 5 MHz WDMA-FDD caies. IV. SIGAL PROESSIG REQUIREMETS FOR WDMA The signal pocessing equiemens fo he physical laye of a WDMA BTS wee esimaed in [1], his assumed an all voice configuaion wih a symbol ae of 15 bi/sec. We assume ha he physical laye signal pocessing equiemens (MIPS) fo a high speed daa channel ae much he same as fo a low speed voice channel. This is he case because he numbe of MIPS is dominaed by he chip-ae pocessing ahe han he symbol ae pocessing he chip-ae (3.84 Mcps) does no change wih vaying symbol ae. Theefoe we use he same figues fo each 384 bi/sec pocessing funcion as pe Table 1. Vaiable Symbol MIPS Symbol MIPS pe DL anspo channel DL ST 69 hip MIPS pe DL conol channel DL 3 hip MIPS pe DL affic channel DL T 3 Symbol MIPS pe UL anspo channel UL ST 70 hip MIPS pe UL access channel pe c UL A 3.3 hip MIPS pe UL pah seach pe c UL P 3.3 hip MIPS pe UL ae eceive UL R TABLE 1 Laye-1 MIPS pe Funcion V. OST FUTIO A cos funcion fo a newo of SDR BTS s was developed in [1] whee eceive is he cos of each fon end eceive, ansmi he cos of each fon end ansmie fixed is he cos of he base hadwae (powe supplies, swich, conolle ec), hen he cos of each BTS is = (5) BTS eceive ansmi fixed Using he esuls of [1] he cos of he newo pe uni aea was deived as

3 A omplexiy os funcion fo a newo of WDMA Basesaions using Sofwae Defined Radio wih High Speed Daa hannels 3 ' β φy = Whee: A = ρt B = ρt ( A + B + ) β UL β 3 P + D ( DLT + DLST + ULR + ULST ) A ST ( DL DLST = c UL + UL + a + ) (6) (') Relaive BTS os pe Uni Aea ' Tem Fixed Tem ell diamee (D) ilomees Fig Relaive os Funcion fo a affic (384 bi/sec) densiy of 150 Elang pe m This esul illusaes ha cos is a sum of he cos of deploying esouces ha incease linealy wih inceasing cell diamee he cos of he fixed esouces (powe supplies, cabines ec) ha decease invesely popoional o he squae of he cell diamee. VI. SPETRUM USAGE D = + + eceive ansmi fixed The esul fom (6) can be simplified o bee explain he shape of he esulan funcion, i.e. 3 ' = (7) 4 By inspecion of Table 1 he consan 3 will be significanly less han 1 he elaive cos funcion can be fuhe simplified o ' (8) 4 The esul is ploed in Figue 1 whee 1 c + is descibed as he Tem 4 / c is he Fixed Tem. Assume ha specum is puchased in blocs of 5 MHz (paied fo FDD) fo he enie aea of he newo a a cos of F pe bloc. Le c be he maximum numbe of 5 MHz caies equied fo he newo. If s is he numbe of subscibes, hen he newo mus povide s T affic channels whee he specum cos is ( F c )/( s T ) pe affic channel. Le be he cos pe uni aea o populae A p wih basesaions. Ou analysis uses he Euopean expeience wih 3G specum aucions as he wos case, see Table. VII. MUD REEIVER c is a funcion of he numbe of uses ha can be suppoed by he fowad evese lins T BTS. By using a MUD eceive he numbe of affic channels in he evese lin can be inceased by a faco of appoximaely 3 [10] wih he same c fo a given scenaio. VIII. SPAE TIME TRASMIT DIVERSITY Fowad lin capaciy can be inceased by using Space Time Tansmi Divesiy (STTD) whee he same signal is ansmied via wo spaially sepaaed anennas wih diffeing ampliude phase. The capaciy gain using STTD is esimaed o be 140% [4]. I is assumed ha hee is no incease in he consumpion of signal pocessing esouces STTD is applied o (6) by inceasing fom 1 o. IX. HIGH SPEED DOW-LIK PAKET AESS Fowad lin capaciy can be inceased by up o 100% [4] (p.83) by using he High Speed Down-Lin Pace Access (HSDPA) pa of he 3GPP sad. We assume ha he

4 A omplexiy os funcion fo a newo of WDMA Basesaions using Sofwae Defined Radio wih High Speed Daa hannels 4 oveall down-lin capaciy impovemen has an uppe bound of 80% by using STTD HSPDA. Theefoe we assume ha wihou using STTD, MUD HSDPA, he up down-lins can suppo [see Appendix 1] a maximum of 3*384 bi/sec = 1.15 Mbi/sec pe caie. By using STTD, MUD HSPDA he up down-lins can suppo a maximum of.8*1.15 Mbi/sec = 3.3 Mbi/sec pe caie. X. UMERIAL RESULTS Based on he fowad powe calculaion fom Appendix II he cos of he ansmie was educed (c.f. [1]) fom 1.5 o 0.5, see Table. The elaive cos (c.f. Fixed Resouce os) pe MHz of specum pe affic channel was calculaed o be 0.1. Vaiable Symbol Values pe BTS Jusificaion Fixed esouce fixed 1 Typical figue cos esouce 0.5 Based on 8 high end cos s Fon-end eceive 1.5 Typical figue eceive cos Fon-end ansmie cos ansmi 0.5 Typical figue. Based on fowad lin powe calculaion. os pe 5 MHz 0.1 Wos case. Based on pe affic Euopean 3G aucion channel esuls TABLE BTS Paamees The paamee values pesened in Table have been nomalized o he cos of he fixed esouces, e.g. if fixed = $ 0,000 hen = $10,000 ec. The elaive cos funcion (compaed wih he minimum cos implemenaion) was evaluaed (wihou STTD, MUD HSDPA wih STTD, MUD HSDPA) using a se of sysem paamees ploed fo a affic densiy of 150 Elang/m, see Figue 3. The fowad evese-lin capaciy was se o 3 affic channels pe caie (Appendix I/II) wihou STTD, MUD HSDPA wih a coesponding maximum cell diamee of 1.9 m. ( ') Relaive BTS cos pe uni aea Sad BTS BTS wih MUD, STTD, HSDPA ell diamee (D) ilomees Fig 3 Relaive os Funcion fo a affic densiy of 150 Elang pe m This illusaes ha he minimum cos SDR WDMA newo is achieved by no limiing cell diamee by using a convenional BTS wihou MUD, STTD HSPDA, i.e. minimum occus fo a cell diamee of 0.6 m whee c is hee (i.e. 15 MHz of specum). Howeve if cell diamee mus be geae han 0.31 m, hen newo cos can be educed by implemening he BTS wih MUD, STTD HSDPA, e.g. cos is educed by 50 % when he cell diamee is 0.73 m. The use of MUD, STTD HSDPA also inceases specum efficiency e.g. c is educed fom 11 (55 MHz) o 4 (0 MHz) fo a cell diamee of 0.49 m. If he newo is specum limied o a value of c =1 hen he cell diamee can incease by 77% fom 0.13 m o 0.3 m by using MUD, STTD HSDPA in a newo aea equied o suppo 150 Elang (384 bi/sec) pe m. XI. OLUSIOS In his pape we have developed a complexiy cos model fo a basesaion in a DS/DMA sysem, modeled lagely on 3GPP. We have shown, fo a give cell size he complexiy cos associaed wih such an SDR implemenaion. We have also shown ha fo a given load ha an opimal cell size exiss which minimizes he oveall sysem cos of he implemenaion. We have also shown ha when he cos of specum is aen ino accoun, he cos of deploying a newo of SDR base saions can be significanly educed by implemening up down-lin capaciy impoving echniques such as MUD, HSDPA STTD. Sofwae Defined Radio base saions have a disinc advanage ove convenional hadwae defined adios as he algoihms fo hese capaciy impoving echniques can be insalled wihou he need fo hadwae modificaion, excep fo he addiion of signal pocessing esouces ( cads) if equied.

5 A omplexiy os funcion fo a newo of WDMA Basesaions using Sofwae Defined Radio wih High Speed Daa hannels 5 APPEDIX I Revese Lin oveage & apaciy The up-lin load equaion [4] (Equaion 8.4) is E / b = 0 (1 ) W / R i sα η (9) UL + s is he numbe of uses pe seco, α is he aciviy aio, W is he speading bwidh, R is he infomaion bwidh, E b / o is he signal o noise aio necessay fo a given qualiy of sevice i is he ohe cell o own cell inefeence aio seen by he base saion eceive. Evaluaing fo WDMA whee α = 1, E b / o = 1.74 (.3 db), i ave = 0.65 Ψ ave = 0.5, he aveage down-lin load faco is 0.6 fo 3 uses pe seco. Using [4] (Equaion 8.18) assuming he mobile eceive noise figue is 7 db, f is 100 dbm. Expessing (11) in logaihmic powe unis Eb / 0 s W / R P ( db) = log + Lave ( db 1 η DL ave (13) oise ise [4] (Equaion 8.9) is equal o 1 1 η UL (10) The oal powe equied fom he powe amplifie is calculaed by To balance efficiency wih coveage we shall dimension fo a noise ise of less han 3dB i.e. a load faco of 0.6. Evaluaing (9) fo WDMA whee α = 1, W=3.84x10 6, R=384 bi/sec, E b / o = 1.5 (1 db) i = 0.65 indicaes ha he evese lin can suppo appoximaely 3 uses pe seco. Using he lin budge [4] (Table bi/sec daa sevice), he allowed popagaion loss is appoximaely 139 db his implies a maximum cell diamee R of appoximaely 1.9 m. APPEDIX II Revese Lin apaciy BTS Powe The sum of he equied fowad powe (Effecive Isoopic Radiaed Powe) fo he affic channels P can be calculaed by using [4] (Equaion 8.17) P = f E WLave s W / R 1 η DL ave b / 0 (11) Whee f is he noise specal densiy of he mobile eceive fon-end, L ave is he aveage pah loss fo all uses in he cell. The aveage down-lin load faco [4] (Equaion 8.16) is / 0 Eb η DLave = sα(1 ψ ave + iave ) (1) W / R Whee Ψ ave is he aveage ohogonaliy faco fo all uses in he seco, i ave is he aveage aio of ohe cell o own cell base saion powe eceived by each use in he seco. P = P + P c (14) Whee P c is he amoun of powe allocaed o he down-lin conol channels. Evaluaing he middle pa of (13) allowing 15% of he powe allocaion fo conol synchonizaion channels (see pg 179 of [4]) we ge 1 P ( dbm) = Lave + 10log (15) Assuming powe conol is used uses ae unifomly disibued houghou he cell, he aveage equied powe will be 6 db less han ha needed on he cell edge [4] (p.178). Evaluaing (15) using he evese lin pah loss esul of 139 db 8dB yields a P (EIRP) of 30 dbm. Assuming 10 db o gain fom ansmi eceive anennas less cable losses, he acual size of he ansmi powe amplifie will be of he ode of 0 dbm pe RF caie. A muli-caie powe amplifie in he ode of 1 Wa will heefoe hle up o 10 caies. Fom his esul we se ansmi o 0.5. REFEREES [1] P. Buns M. Reed, A omplexiy os Funcion fo he Signal Pocessing in a WDMA Basesaion fo dimensioning of a Sofwae Defined Radio., (Submied o I 004) Sepembe 003. [] P. Buns, Sofwae Defined Radio fo 3G, Aech House 00. [3] K. S. Gilhousen, I. M. Jacobs, R. P. Padovani, A. J. Viebi, On he apciy of a ellula DMA Sysem, IEEE

6 A omplexiy os funcion fo a newo of WDMA Basesaions using Sofwae Defined Radio wih High Speed Daa hannels 6 Tansacions On Vehicula Technology, Vol 40, o, May [4] H. Holma A. Tosala, WDMA fo UMTS: Radio Access fo Thid Geneaion Mobile ommunicaions, Wiley 00 [5] J. Laiho, A. Wace T. ovosad, Radio ewo Planning Opimisaion fo UMTS, Wiley 00. [6] Lee, J.S., Mille, L.E., "DMA Sysems Engineeing Hboo", Aech House [7] K. Tuschu P Tan-Gia, Spaial Taffic Esimaion haaceizaion fo Mobile ommunicaion ewo Design, IEEE Jounal on Seleced Aeas in ommunicaion, Vol 16, o 5, June [8] Q. Hao, B. Soong, E. Gunawan, J. Ong Z. Li, A Low-os ellula Mobile ommunicaion Sysem: A Heiachical Opimizaion ewo Resouce Planning Appoach, IEEE Jounal on Seleced Aeas in ommunicaion, Vol 15, o 7, Sepembe [9] I. Sesa. Mayam, A Sofwae Radio Achiecue fo Linea Muliuse Deecion, IEEE Jounal on Seleced Aeas in ommunicaion, Vol 17, o 5, May [10] M. Reed, P. Heach, J. Mauche, ``An ieaive muliuse deecion eceive fo 3GPP wih anenna aays : Pefomance in ems of BER, cell size capaciy,'' in Mobile ommunicaions Technology onfeence 3G00, (London U.K.), May 00. [11] I.T.U, Recommendaion ITU-R M.15 Guidelines fo Evaluaion of Radio Tansmission Technologies fo IMT-000, [1] E.T.S.I., TR Univesal Mobile Telecommunicaions Sysem (UMTS) Selecion pocedues fo he choice of adio ansmission echnologies of he UMTS, 1998.